$L_1 = \{\;a^{n+m}.b^n . a^m \;|\; n,m ≥ 0 \;\} = \{\;a^{m}.a^n.b^n . a^m \;|\; n,m ≥ 0 \;\} $
Push all a's, Pop every a for one b,
Now there are only m number of a's in stack,
Now, Pop every a for one a, ==> if it is empty stack, then accept
∴ CFL
$L_2 = \{\;a^{n+m}.b^{n+m} . a^{n+m} \;|\; n,m ≥ 0 \;\} = \{\;a^{x}. b^x . a^x \;|\; x ≥ 0 \;\} $ where x = n+m
it is CSL but not CFL